Cook spaghetti according to package directions until just tender.
Meanwhile, in a small saucepan combine clam sauce, spinach, oregano and garlic powder.
Bring to a boil.
Reduce heat and simmer, covered, for 5 minutes.
Stir in Parmesan cheese.
Drain spaghetti.
Place in a serving bowl.
Top with sauce.
Toss gently.